Read next word in java | 易学教程

问题

I have a text file that has following content:

ac und
accipio annehmen
ad zu
adeo hinzugehen
...

I read the text file and iterate through the lines:

Scanner sc = new Scanner(new File(\"translate.txt\"));
while(sc.hasNext()){
 String line = sc.nextLine();       
}

Each line has two words. Is there any method in java to get the next word or do I have to split the line string to get the words?

回答1:

You do not necessarily have to split the line because java.util.Scanner's default delimiter is whitespace.

You can just create a new Scanner object within your while statement.

    Scanner sc2 = null;
    try {
        sc2 = new Scanner(new File("translate.txt"));
    } catch (FileNotFoundException e) {
        e.printStackTrace();  
    }
    while (sc2.hasNextLine()) {
            Scanner s2 = new Scanner(sc2.nextLine());
        while (s2.hasNext()) {
            String s = s2.next();
            System.out.println(s);
        }
    }

回答2:

You already get the next line in this line of your code:

 String line = sc.nextLine();

To get the words of a line, I would recommend to use:

String[] words = line.split(" ");

回答3:

Using Scanners, you will end up spawning a lot of objects for every line. You will generate a decent amount of garbage for the GC with large files. Also, it is nearly three times slower than using split().

On the other hand, If you split by space (line.split(" ")), the code will fail if you try to read a file with a different whitespace delimiter. If split() expects you to write a regular expression, and it does matching anyway, use split("\\s") instead, that matches a "bit" more whitespace than just a space character.

P.S.: Sorry, I don't have right to comment on already given answers.

回答4:

you're better off reading a line and then doing a split.

File file = new File("path/to/file");
String words[]; // I miss C
String line;
HashMap<String, String> hm = new HashMap<>();
try (BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(file), "UTF-8")))
{
    while((line = br.readLine() != null)){
        words = line.split("\\s");
        if (hm.containsKey(words[0])){
                System.out.println("Found duplicate ... handle logic");
        }
        hm.put(words[0],words[1]); //if index==0 is ur key
    }

} catch (FileNotFoundException e) {
        e.printStackTrace();
} catch (IOException e) {
        e.printStackTrace();
}

回答5:

You can just use Scanner to read word by word, Scanner.next() reads the next word

try {
  Scanner s = new Scanner(new File(filename));

  while (s.hasNext()) {
    System.out.println("word:" + s.next());
  }
} catch (IOException e) {
  System.out.println("Error accessing input file!");
}

来源：https://stackoverflow.com/questions/4574041/read-next-word-in-java

标签

java

java.util.scanner